I would say it all depends on the efficiency of your study. Some people spend 3 months to get a high score while some only spend a few weeks.
Make your own plan and make sure you follow it. At the end, test your knowledge by doing a lot of practice tests. Take the exam when you feel comfortable.
Everyone studies differently. I find that a high score comes with assessing how you learn, building a study schedule based on that, and following that study schedule to a T.